Magnetic field effects cholesteric-nematic

It is reasonable to assume that the hne shapes shown in Fig. 13 reflect the presence of helical structures in cholesteric LCs even in the strong magnetic field, and it can safely be assumed that the helical structure directions were perpendicular to the magnetic field, as proposed by Meyer [14]. At first, Eq. (18), in which uniaxial rotation is assumed, was used to simulate the hne shapes in Fig. 13. According to the field effect on cholesteric LCs, in which, macroscopically, cholesteric LCs are spontaneously twisted nematics, Eq. (18) was integrated in terms of / l, which should have provided the pseudo-line shapes of helical structures in the magnetic field. However, it was very difficult or nearly impossible to reasonably reproduce the experimental line shape with our analysis. Therefore, the concept of biaxiality for... 

Contrary to cholesterics and nematics, not much work has been done regarding the effects of external fields on smectics. The possibility of a Freedericksz transition in a smectic liquid crystal by an external dc magnetic field has been considered by Helfrich, Rapini, Hurault, and Meirovitch et The results show that all transitions... 

The magnetic field also widens the temperature-concentration region of the existence of the LC phase. This effect is related to the cholesteric liquid crystal - nematic liquid crystal phase transition and the orientation of macromolecules in the direction parallel to the magnetic field lines. In this case, large supramolecular structures (domains) develop in solutions. The effect of magnetic field on the variation in LC transitions with the pwlymer concentration in solution shows an extremal pattern. Figures 15 and 16 demonstrate the concentration dependences of AT for HPCl- DMAA, HPC-3-DMAA, and HPC-l-water systems measured at various magnetic field intensities. 

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